What Is the D-Dimer Test?

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The D-dimer test is a blood test doctors can use to rule out whether you have a severe blood clot. It's beneficial if your doctor suspects you have a blood clot in your lung or deep within a vein of your leg or pelvis.

These conditions can be fatal. Getting prompt treatment increases your chances of surviving and avoiding other medical problems. Read on to learn more about the D-dimer test, how doctors use it, and its limitations.

d-dimer test

Verywell / Brianna Gilmartin

What Is D-Dimer?

D-dimer is a substance involved in the body's healing process. When you get hurt and bleed, your body uses proteins to clump up your blood. The clot that forms plugs the damaged vessel.

Once the bleeding stops, your body sends out other proteins to slowly break down the clot. Afterward, you end up with fragments of D-dimer in your blood.

These protein fragments usually dissolve over time. However, if a clot doesn't break up or another one forms, you'll have high levels of D-dimer in your blood.

Purpose of the Test

The D-dimer test involves a simple blood draw. A health care provider will use a thin needle to get a sample of your blood and analyze it. Results are ready within minutes.

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Anyone can get a blood clot. Doctors usually order a D-dimer test to rule out two dangerous types of blood clots.

  • Deep vein thrombosis or DVT: a blood clot that forms deep within a vein
  • Pulmonary embolism or PE: a blood clot that travels from other parts of the body and ends up in an artery of your lungs.


As many as 100,000 deaths occur each year in the US due to DVT and PE.The symptoms you may have include:

  • Swelling or redness, usually in the lower leg but sometimes in the thigh, pelvis, or an arm
  • Pain in the leg, thigh, pelvis, arm
  • Difficulty breathing
  • Fast heartbeat
  • Chest pain
  • Sweating a lot

Getting prompt treatment increases your chances of surviving PE and DVT. It also helps you avoid other medical problems that can hurt your quality of life.

When Is It Useful?

Diagnosing these conditions can be tricky. One study found that nearly 70% of people treated in emergency rooms with symptoms of DVT aren't diagnosed with the disorder.

Doctors used to have to send all blood samples to a central lab for analysis. This caused delays and meant the test couldn't be used for emergencies. So doctors were forced to send patients for expensive imaging tests instead.

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In recent years, the US Food and Drug Administration has approved several rapid D-dimer tests. These tests provide doctors with a fast, inexpensive way to rule out DVT or PE.

Interpreting Results

Results can vary depending on the test your doctor used and the design. Doctors need to know the ranges of normal and abnormal levels for the test they're using.

Normal or Abnormal?

If your results are in the lower range, your doctor can safely rule out a blood clot. If your results come back abnormal or high, you'll likely need more tests. The D-dimer test cannot be the sole basis to diagnose DVT or PE.

Why Is the D-Dimer High?

Many diseases, treatments, and lifestyle factors can raise your D-dimer levels. That's why it is essential to answer all the medical history questions thoroughly. People with blood clots often have one or more of the same risk factors. They include:

Medical conditions and treatments:

  • Heart disease: Patients with unstable angina or who have had a heart attack have higher levels of D-dimer and a higher risk of future blood clots.
  • Cancer: Some cancers can increase the risk of a blood clot.
  • Cancer treatment: Chemotherapy and certain breast cancer drugs can increase the risk of blood clots.
  • Treatment with estrogen: Birth control pills and hormone replacement therapy can increase the risk of DVT and PE.
  • Surgery: Patients who have had major surgery, like a hip or knee replacement, have a higher risk of a blood clot. (Drugs are prescribed to prevent this.)
  • Infectious diseases: Covid-19 and pneumonia can cause inflammation and trigger blood clots.
  • Kidney disease: Increases inflammation, the risk of a blood clot
  • Liver cirrhosis: Elevated D-dimer levels and bleeding are associated with a higher risk of death.
  • Pregnancy: D-dimer levels rise two-fourfold by delivery.Women have an increased risk of DVT or PE for up to 3 months after delivery.

Other risk factors:

  • Age: People over 60 years of age have a higher risk of blood clots.
  • Cigarette smoking: Increases the risk of blood clots.
  • Race: African Americans have higher levels of D-dimer compared to people of European ancestry.
  • Gender: Women have higher levels of D-dimer than men.
  • Obesity: increases the risk of blood clot
  • Sedentary lifestyle: Not exercising or not moving for an extended period can increase the risk of DVT or PE. An example is a long plane ride.

So doctors will order other tests to make sure you don't have PE or DVT. These tests may include:

  • More blood tests: To check your platelets and see if you have a bleeding disorder
  • Ultrasonography: A test that uses high-frequency sound waves to take pictures of your blood vessels, tissue, and organs
  • Ventilation-perfusion lung scan: Tests that use a radioactive substance to help doctors see if air and blood can move through the lungs or if you have a blockage
  • Computed tomography angiography: A test where you get an IV of a special dye. Doctors use a CT scan to take high-definition pictures from different angles. The dye lights up the blood vessels and tissue they need to check for blood clots.

Pulmonary Embolus

Patients with a low risk of blood clots and whose D-dimer levels are in the lower to middle range likely don't have pulmonary embolus. Studies show the test is comparable to ultrasonography or CT angiography in ruling out PE. If your test results show high levels, you will need more tests. Also, many people who've had a recent PE will still have elevated D-dimer levels. So the test won't be helpful for them.

Deep Vein Thrombosis

Nearly all patients with DVT have elevated D-dimer levels. This makes the test especially helpful in ruling out the condition. It also helps if your symptoms aren't that clear. If your levels are high, your doctor will order more tests.  

Other Medical Conditions

Ruling out DVT and PE are the main reasons doctors order D-dimer tests. However, the test can help doctors evaluate and manage other severe conditions that involve blood clots. These include:

  • Coronary artery disease: People with severe heart disease have higher levels of D-dimer. People treated for a heart attack but still have elevated D-dimer levels have an increased risk of another heart attack or dying from one.
  • Stroke: Higher levels of D-dimer are associated with an increased risk of stroke.
  • Disseminated intravascular coagulation: A rare disease where blood clots form in vessels throughout the body. Elevated D-dimer levels are part of the scoring test for DIC.
  • Hyperfibrinolysis: A blood clotting disorder similar to DIC. The d-dimer test helps evaluate this disorder.

Summary

Doctors may order a D-dimer test if they suspect you might have a dangerous blood clot. The test helps doctors rule out two conditions that can be fatal: deep vein thrombosis, a blood clot in a vein, often a lower leg, and pulmonary embolism, a blood clot in the lung.

A negative test result means you probably don't have a blood clot. Usually, you won't need any further tests. However, if your results come back abnormal, that doesn't necessarily mean you have a clot. The test isn't definitive. Your doctor will likely order other tests.

A Word From Verywell

Doctors used to have to send all patients they suspected of having DVT or PE for imaging tests. This was expensive and time-consuming. The D-dimer test is a fast, inexpensive blood test they can use to rule out a dangerous blood clot. If your results come back low, you likely don't have to worry.

However, many diseases, treatments, and lifestyle factors can increase your D-dimer levels. So if your results come back abnormal, you'll need more tests to confirm you don't have a blood clot.

Frequently Asked Questions

  • Why am I getting a D-dimer test?

    Doctors order this test to rule out the possibility of a severe blood clot. The two conditions it is used for the most are pulmonary embolism, a blood clot in your lung, and deep vein thrombosis, a blood clot deep within a vein, usually a lower leg.

  • Does the D-dimer test hurt?

    It is a simple blood test. Your health care provider will use a thin needle to get a sample of your blood and analyze it.

  • How soon will I get my results?

    You will get your results within minutes.

  • What do the results mean?

    If your results come back low, then you probably don't have a blood clot. If they come back high or abnormal, that doesn't mean you have a blood clot. There may be other reasons why your results are high. Your doctor will need to order more tests.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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    1. Centers for Disease Control and Prevention. Data and statistics on venous thromboembolism. Updated March 14, 2019.
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Additional Reading
  • Blood Clot in the Lungs.Prompt treatment may be lifesaving. Mayo Clinic Health Letters. 2012;30(9):1-3. https://pubmed.ncbi.nlm.nih.gov/23097809/Published September 30, 2012


  • Centers for Disease Control and Prevention. Data and Statistics on Venous Thromboembolism. https://www.cdc.gov/ncbddd/dvt/data.html. Page last reviewed: February 7, 2020

  • Centers for Disease Control and Prevention. Deep Vein Thrombosis & Pulmonary Embolism. cdc.gov/travel/yellowbook/2020/travel-by-air-land-sea/deep-vein-thrombosis-and-pulmonary-embolism. Page last reviewed: June 24, 2019

  • Kottke-Marchant,Kandice, Rogers, Joyce H. D-dimer to Rule Out Venous Thromboembolism. Cleveland Clinic website. https://clevelandcliniclabs.com/wp-content/assets/pdfs/technical-briefs/d-dimer-26156.pdf. Revised March 31, 2014

  • Martin KA, Molsberry R, Cuttica MJ, Desai KR, Schimmel DR, Khan SS. Time trends in pulmonary embolism mortality rates in the united states, 1999 to 2018. Journal of the American Heart Association. 2020;9(17):e016784. https://doi.org/10.1161/JAHA.120.016784

  • Schutte T, Thijs A, Smulders YM. Never ignore extremely elevated D-dimer levels: they are specific for serious illness. Neth J Med. 2016;74(10):443-448. https://www.njmonline.nl/getpdf.php?id=1790


  • Weitz JI, Fredenburgh JC, Eikelboom JW. A test in context: D-dimerJ Am Coll Cardiol. 2017; 70:2411. http://doi:10.1016/j.jacc.2017.09.024.